In the prior art, functional polymers are often used as high-resolution lithographic materials in the manufacture of LSI. In accordance with the recent advance of LSI technology toward higher density, the resist material is also required to have a high degree of resolution and development ability. To meet this requirement, in the case of novolak resin which is one of prior art resist materials, a technique of fractionation is utilized to control the molecular weight of the novolak resin for increasing the degree of resolution and development ability (see Japanese Patent Application Kokai No. 1217542/1987). The fractionation technique is, however, complicated in operation and time consuming.
One recently proposed replacement for prior art resist materials is a class of chemically amplified resist materials. Among such resist materials, those compounds having a functional group which is readily eliminatable with acid and showing a substantial difference in solubility before and after the elimination are preferred largely because of ease of processing. Styrene derivatives having good plasma resistance are known desirable from this point of view, but not successful in meeting the recent increasingly rigorous demand.